Manufacture of concrete slabs and structures is now commonly achieved by pre-casting techniques. Pre-cast manufacture of concrete slabs and structures is becoming the preferred method for many construction applications including industrial, commercial and retail applications.
Typically, pre-casting is performed on a steel bed. Steel beds can be constructed to have a surface with a relatively high level of precision. This allows concrete slabs and structures to be manufactured to an associated level of accuracy.
Edge or perimeter moulds are used to produce concrete slabs and structures of a certain shape. These moulds are commonly referred to as sideforms. Securing the sideforms in position on a steel bed may involve the use of magnetic clamps. However, in practice the surface of a steel bed is not completely uniform. Variations in height at certain regions of the bed may reach approximately 5 mm. For steel beds which are recognised to be of a relatively high quality, variations of approximately 3 mm between the high and low points are generally present. Such height variation can reduce the holding force a magnetic clamp exerts on a sideform, or cause the sideform to be supported in a position that is not perpendicular to the bed.